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Magnetic Susceptibility of a Crystalline Free Radical

Description: The entirety of the investigation discussed in this paper was confined to a study of the spin resonance properties of unpaired electrons of an organic free radical. In the remainder of the paper the theory of electron spin resonance, the apparatus used in the investigation, and the experimental results obtained are discussed in that order.
Date: June 1962
Creator: Smith, William C.
Partner: UNT Libraries

Corrosion resistance and magnetic susceptibility

Description: From summary: "On the basis of the tests described herein, the corrosion characteristics of T-347 welded stainless steel are found not to be affected by the magnetic properties of the welds even though these properties are likely the result of the presence of the ferritic structure."
Date: March 7, 1949
Creator: Koenig, W. W. & Heckman, R. L.
Partner: UNT Libraries Government Documents Department

Disorder and size effects on Kondo interactions and magneticcorrelations in CePt2 nanoscrystals

Description: The evolution of the Kondo effect and magnetic correlations with size reduction in CePt{sub 2} nanoparticles (3.1-26 nm) is studied by analysis of the temperature-dependent specific heat and magnetic susceptibility. The antiferromagnetic correlations diminish with size reduction. The Kondo effect predominates at small particle size with trivalent, small Kondo temperature (T{sub K}) magnetic regions coexisting with strongly mixed valent, large T{sub K} nonmagnetic regions. We discuss the role of structural disorder, background density of states and the electronic quantum size effect on the results.
Date: December 12, 2006
Creator: Chen, Y.Y.; Huang, P.H.; Ou, M.N.; Wang, C.R.; Yao, Y.D.; Lee,T.K. et al.
Partner: UNT Libraries Government Documents Department

deHAAS-vanALPEN effect in URh$sub 3$ and UIr$sub 3$

Description: Measurements of the deHaas-vanAlphen effect were performed in the intermetallic compounds URh$sub 3$ and UIr$sub 3$. Complex spectra were observed in both materials. Effective mass measurements were made for several orbits in URh$sub 3$ and values as large as 5.3 m$sub 0$ were observed. The relatively complete data in URh$sub 3$ are consistent with a complex multiply-connected Fermi surface which is in qualitative agreement with band structure calculations. The largest frequency branches in UIr$sub 3$ appear to have the same topology as their corresponding branches in URh$sub 3$. In addition, a number of closed low- mass surfaces exist in UIr$sub 3$ and are discussed in terms of the calculations for URh$sub 3$. (auth)
Date: September 1, 1975
Creator: Arko, A.J.; Brodsky, M.B.; Crabtree, G.W.; Karim, D.; Windmiller, L.R. & Ketterson, J.B.
Partner: UNT Libraries Government Documents Department

Crystallographic texture determinations from inverse susceptibility measurements

Description: Determination of the quantitative relationship between crystallographic texture and magnetic properties in advanced permanent magnets may be hampered by complex microstructures, which complicate methods that rely on diffraction, or by interparticulate interactions, which adversely affect methods based on magnetic remanence measurements. To this end, new techniques in the determination of texture of bulk permanent magnets are being explored to overcome these inherent experimental difficulties. The analysis of inverse paramagnetic susceptibility measurements constitutes a new method to investigate crystallographic texture. Such measurements also provide Curie temperature data, which is sensitive to chemical changes that may have occurred in the magnetic phase during processing. The mathematical formalism underlying the analysis of inverse susceptibility measurements is outlined, and is used to evaluate magnetic measurements taken from a series of Nd{sub 2}Fe{sub 14}B magnets that have been processed by different means, and thus contain different degrees of texture. While this method does provide qualitative information concerning the relative crystallographic alignment of magnet samples, it needs calibration to obtain an explicit value for a texture order parameter.
Date: October 1, 1996
Creator: Lewis, L.H. & Welch, D.O.
Partner: UNT Libraries Government Documents Department

Magnetism in BaCoS{sub 2}

Description: BaCoS{sub 2} is a layered Mott-Hubbard insulator that orders antiferromagnetically near 300 K. We report magnetic susceptibility measurements on polycrystalline BaCoS{sub 2} from 77 K to 800 K, and in- and out-of-plane measurements on single crystals from 2 K to 350 K. We also report a powder neutron refinement of the magnetic structure of BaCoS{sub 2}. The neutron measurements indicate that the moments lie in the plane, and that the magnetic unit cell is the same as the (orthorhombic) chemical cell. The ordered moment obtained from the neutron refinement is close to 3 {mu}{sub B} indicating that the Co ions are in the high-spin (S = 3/2) configuration. The effective moment inferred from the high temperature susceptibility, p = 5.26 {mu}{sub B} is also consistent with high-spin Co{sup +2}.
Date: August 1996
Creator: Mandrus, D.; Chakoumakos, B. C.; Fernandez-Baca, J. A.; Nagler, S. E.; Sales, B. C. & Sarrao, J. L.
Partner: UNT Libraries Government Documents Department

Two-dimensional intrinsic and extrinsic ferromagnetic behavior of layered La{sub 1.2}Sr{sub 1.8}Mn{sub 2}O{sub 7} single crystals

Description: The low-field magnetization M and susceptibility {chi} are reported for the two-layered Ruddleson-Popper phase SrO(La{sub 1{minus}x}Sr{sub x}MnO{sub 3}){sub 2} for x = 0.4 (denoted La{sub 1.2}Sr{sup 1.8}Mn{sub 2}O{sub 7}) with an in-plane magnetic easy axis. As T approaches the Curie temperature (T{sub C} = 116 K) on cooling, where the metal-insulator transition occurs in zero-field, {chi} diverges as H{sup {minus}1/{delta}{prime}}, with {delta}{prime} = 21 {+-} 5. Also, near an extrinsic Curie transition attributed to {approximately} 0.1% volume fraction of intergrowths at T* = 2.47T{sub C}, M scales as (1 {minus} T/T*){sup {beta}}, with {beta} = 0.25 {+-} 0.02. These results can be understood within the context of 2D XY models, and provide a new perspective of the layered manganites.
Date: June 6, 1997
Creator: Potter, C. D.; Swiatek, M.; Bader, S. D.; Argyriou, D.N.; Mitchell, J. F.; Miller, D. J. et al.
Partner: UNT Libraries Government Documents Department

CMR of Co/Cu multilayers with reduced hysteresis and low-field response

Description: We present the results of a systematic study on optimization of the giant magnetoresistance (GMR) response in Co/Cu multilayers (MLs) for copper layer thickness near the second oscillatory peak. Co/Cu MLs with alternating thick (t(1)Co) and thin (t(2)Co) layers have been prepared in the from of [Cot(1)CoA/Cu20A/Cot(2)CoA/Cu20A]15. We have found that the magnetoresistive hysteresis of these MLs is reduced with decreasing t(2)Co and has disappeared when t(2)Co<4.5A. We have obtained an optimal GMR response with a field sensitivity of 0. 013%/Oe over a field region of -60 Oe centered at -50 Oe. This architecture may enable the use of Cu/Co MLs in low-field magnetic sensor applications.
Date: February 1, 1997
Creator: Mao, M.; Gibbons, M.; Law, B.; Grabner, F.; Veron, S. & Cerjan, C.
Partner: UNT Libraries Government Documents Department

Field test of a wideband downhole EM transmitter

Description: A viable large bandwidth TEM transmitter can be constructed using very conventional means although in the present case the effective magnetic permeability of the solenoid core was lower than expected. Only a small number of turns can be used too maintain reasonably low inductance. This has to be compensated with the use of large currents. In this case, good ventilation must be provided to avoid overheating the electronics. In our case the most temperature sensitive element was the optic fiber transmitter which usually failed after about an hour of operation. Care must also be taken to guarantee balance between the negative and positive pulses as this improves the signal/noise ratio. Finally, we reiterate the need to review the origin and nature of the trigger pulse so that consistent properly clocked data can be acquired. In spite of the unlimited nature of the RFS tests which prevented us from acquiring data suitable for a direct demonstration of the wavefield transform, we did secure high quality wideband data that confirmed the proper performance of the prototype transmitter. We are certain that this equipment can now be used in an oil-field environment to acquire data suitable for a practical verification of the wavefield transform.
Date: July 1, 1999
Creator: Becker, Alex; Lee, Ki Ha & Reginato, Lou
Partner: UNT Libraries Government Documents Department

Moessbauer Spectra and Magnetic Susceptibilities of Cs{sub 2}NpCl{sub 6}, (TMA){sub 2}NpCl{sub 6}, and (TEA){sub 2}NpCl{sub 6}

Description: This paper reports additional information obtained from low-temperature magnetic susceptibilities and Moessbauer spectra on Cs{sub 2}NpCl, ((Ch{sub 3}){sub 4}N){sub 2}NpCl{sub 6}, and ((C{sub 2}H{sub 4}){sub 4}N){sub 2}NpCl{sub 6}. The structures of these compounds are inferred from their isostructural uranium and plutonium analogues and the infrared spectral studies.
Date: March 15, 2001
Creator: Karraker, D.G.
Partner: UNT Libraries Government Documents Department

Spin-density-wave magnetism in dilute copper-manganese alloys

Description: Elastic neutron-scattering measurements on two samples of Cu alloyed with 1.3% Mn and 0.55% Mn show that the spin-density-wave (SDW) features found in more concentrated alloys persist in the limit of very dilute alloys. These features consist of temperature-dependent incommensurate peaks in magnetic neutron scattering, with positions and strengths which are fully consistent with those in the concentrated alloys. The implications of these measurements are twofold. First, it is clear from this data that SDW magnetic ordering occurs across the entire range of CuMn alloys which have typically been interpreted as spin glasses. Second, the more fundamental significance of this work is the suggestion via extrapolation that a peak in the magnetic susceptibility x(q) occurs in pure copper, at a value of q given by the Fermi-surface diameter 2k{sub F}.
Date: February 1, 1995
Creator: Lamelas, F.J.; Werner, S.A.; Shapiro, S.M. & Mydosh, J.A.
Partner: UNT Libraries Government Documents Department

Periodic arrays of pinning centers in thin vanadium films.

Description: Commensurability effects between the superconducting flux line lattice and a square lattice (period d=1{micro}m and diameter D=0.4{micro}m) of submicron holes in 1500 {angstrom} vanadium films were studied by atomic force microscopy, DC magnetization, AC susceptibility, magnetoresistivity and I-V measurements. Peaks in the magnetization and critical current at matching fields are found to depend nonlinearly upon the value of external AC field or current, as well as the inferred symmetry of the flux line lattice.
Date: July 13, 1997
Creator: Brueck, S. R. J.; Chung, K.; Crabtree, G.; DeLong, L. E.; Hesketh, P. J.; Ilic, B. et al.
Partner: UNT Libraries Government Documents Department


Description: Surface exploration techniques have been employed in separate study areas on the Fort Peck Reservation in northeastern Montana. Anomalies associated with hydrocarbon seepage are documented in all three areas and a variety of surface exploration techniques can be compared. In a small area with established production, Head Gas and Thermal Desorption methods best match production; other methods also map depletion. In a moderate-size area that has prospects defined by 3D seismic data, Head Gas along with Microbial, Iodine, and Eh soil anomalies are all associated with the best hydrocarbon prospect. In a large area that contains many curvilinear patterns observed on Landsat images, that could represent micro-seepage chimneys, results are inconclusive. Reconnaissance mapping using Magnetic Susceptibility has identified a potential prospect; subsequent Soil Gas and Head Gas surveys suggest hydrocarbon potential. In the final year of this project the principle contractor, the Fort Peck Tribes, completed a second survey in the Wicape 3D Seismic Prospect Area (also known as Area 6 in Phase I of the project) and sampled several Landsat image features contained in the Smoke Creek Aeromag Anomaly Area (also known as Area 1 in Phase II of the project). Methods determined to be most useful in Phases I and II, were employed in this final Phase III of the study. The Southwest Wicape seismic anomaly was only partially confirmed. The abundant curvilinears proposed to be possible hydrocarbon micro-seepage chimneys in the Smoke Creek Area were not conclusively verified as such. Insufficient sampling of background data precludes affirmative identification of these mostly topographic Landsat features as gas induced soil and vegetation anomalies. However relatively higher light gas concentrations were found associated with some of the curvilinears. Based on the findings of this work the Assiniboine & Sioux Tribes of the Fort Peck Reservation intend to utilize surface hydrocarbon ...
Date: June 30, 2003
Creator: Monson, Lawrence M.
Partner: UNT Libraries Government Documents Department

Assessment of Hydrocarbon Seepage on Fort Peck Reservation, Northeast Montana: A Comparison of Surface Exploration Techniques

Description: Surface exploration techniques have been employed in separate study areas on the Fort Peck Reservation in northeastern Montana. Anomalies associated with hydrocarbon seepage are documented in all three areas and a variety of surface exploration techniques can be compared. In a small area with established production, head gas and thermal desorption methods best match production; other methods also mapped depletion. In a moderate-size area that has prospects defined by 3D seismic data, head gas along with microbial, iodine, and Eh soil anomalies are all associated with the best hydrocarbon prospect. In a large area that contains many curvilinear patterns observed on Landsat images, results are preliminary. Reconnaissance mapping of magnetic susceptibility has identified a potential prospect; subsequent soil gas and head gas surveys suggest hydrocarbon potential.
Date: September 9, 2002
Creator: Monson, Lawrence M.
Partner: UNT Libraries Government Documents Department

Training effects and the microscopic magnetic structure of exchange biased Co/CoO bilayers.

Description: Exchange bias of a partially oxidized thin film of ferromagnetic Co was studied by magnetization measurements and polarized neutron reflectivity (PNR). The magnetization curve shows strong effects of training with cycling of the magnetic field. Reflectivity measurements with the field parallel to the cooling field showed the onset of spin-dependent diffuse scattering--off the specular reflection--after a training cycle. Such scattering, of the Yoneda type, is due to misaligned Co domains possibly close to the Co/CoO interface. Subjecting the field cooled Co/CoO pair to a field perpendicular to the cooling field causes a rotation of the magnetization. PNR measurements confirmed earlier susceptibility studies by indicating that the rotation of the magnetization is reversible in fields up to 400 Oe. The rotation of the magnetization of Co is uniform across the film thickness.
Date: September 1, 1999
Creator: Berger, A.; Dahlberg, E. D.; Felcher, G. P.; Hill, B. K. & te Velthius, S. G. E.
Partner: UNT Libraries Government Documents Department

Dynamic magnetic susceptibility of systems with long-range magnetic order

Description: The utility of the TDR as an instrument in the study of magnetically ordered materials has been expanded beyond the simple demonstration purposes. Results of static applied magnetic field dependent measurements of the dynamic magnetic susceptibility, ?, of various ferromagnetic (FM) and antiferromagnetic (AFM) materials showing a range of transition temperatures (1-800 K) are presented. Data was collected primarily with a tunnel diode resonator (TDR) at different radio-frequencies ({approx}10-30 MHz). In the vicinity of TC local moment ferromagnets show a very sharp, narrow peak in ? which is suppressed in amplitude and shifted to higher temperatures as the static bias field is increased. Unexpectedly, critical scaling analysis fails for these data. It is seen that these data are frequency dependent, however there is no simple method whereby measurement frequency can be changed in a controllable fashion. In contrast, itinerant ferromagnets show a broad maximum in ? well below TC which is suppressed and shifts to lower temperatures as the dc bias field is increased. The data on itinerant ferromagnets is fitted to a semi-phenomenological model that suggests the sample response is dominated by the uncompensated minority spins in the conduction band. Concluding remarks suggest possible scenarios to achieve frequency resolved data using the TDR as well as other fields in which the apparatus may be exploited.
Date: May 15, 2009
Creator: Vannette, Matthew Dano
Partner: UNT Libraries Government Documents Department

Linear and nonlinear wave propagation in negative refractionmetamaterials

Description: We discuss linear and nonlinear optical wave propagation in a left-handed medium (LHM) or medium of negative refraction (NRM). We use the approach of characterizing the medium response totally by a generalized electric polarization (with a dielectric permittivity {tilde {var_epsilon}}(w, {rvec k})) that can be decomposed into a curl and a non-curl part. The description has a one-to-one correspondence with the usual approach characterizing the LHM response with a dielectric permittivity {var_epsilon}&lt;0 and a magnetic permeability {mu}&lt;0. The latter approach is less physically transparent in the optical frequency region because the usual definition of magnetization loses its physical meaning. Linear wave propagation in LHM or NRM is characterized by negative refraction and negative group velocity that could be clearly manifested by ultra-short pulse propagation in such a medium. Nonlinear optical effects in LHM can be predicted from the same calculations adopted for ordinary media using our general approach.
Date: May 29, 2003
Creator: Agranovich, V.M.; Shen, Y.R.; Baughman, R.H. & Zakhidov, A.A.
Partner: UNT Libraries Government Documents Department

Synthesis, structure, magnetism, and optical properties of theordered mixed-lanthanide sulfides gamma-LnLn'S3 (Ln=La, Ce; Ln'=Er, Tm,Yb)

Description: {gamma}-LnLn{prime}S{sub 3} (Ln = La, Ce; Ln{prime} = Er, Tm, Yb) have been prepared as dark red to black single crystals by the reaction of the respective lanthanides with sulfur in a Sb{sub 2}S{sub 3} flux at 1000 C. This isotypic series of compounds adopts a layered structure that consists of the smaller lanthanides (Er, Tm, and Yb) bound by sulfide in six- and seven-coordinate environments that are connected together by the larger lanthanides (La and Ce) in eight- and nine-coordinate environments. The layers can be broken down into three distinct one-dimensional substructures containing three crystallographically unique Ln{prime} centers. The first of these is constructed from one-dimensional chains of edge-sharing [Ln{prime}S{sub 7}] monocapped trigonal prisms that are joined to equivalent chains via edge-sharing to yield ribbons. There are parallel chains of [Ln{prime}S{sub 6}] distorted octahedra that are linked to the first ribbons through corner-sharing. These latter units also share corners with a one-dimensional ribbon composed of parallel chains of [Ln{prime}S{sub 6}] polyhedra that edge-share both in the direction of chain propagation and with adjacent identical chains. Magnetic susceptibility measurements show Curie-Weiss behavior from 2 to 300 K with antiferromagnetic coupling, and no evidence for magnetic ordering. The {theta}{sub p} values range from -0.4 to -37.5 K, and spin-frustration may be indicated for the Yb-containing compounds. All compounds show magnetic moments substantially reduced from those calculated for the free ions. The optical band gaps for {gamma}-LaLn{prime}S{sub 3} (Ln{prime} = Er, Tm, Yb) are approximately 1.6 eV, whereas {gamma}-CeLn{prime}S{sub 3} (Ln{prime} = Er, Tm, Yb) are approximately 1.3 eV.
Date: December 12, 2006
Creator: Jin, G.B.; Choi, E.S.; Guertin, R.P.; Brooks, J.S.; Bray, T.H.; Booth, C.H. et al.
Partner: UNT Libraries Government Documents Department

Radiation Damage Effects on the Magnetic Properties of Pu(1-x)Am(x) (x=0.224)

Description: Pu(Am) is stable in the fcc {delta}-phase from a few atomic percent to nearly 80 atomic percent Am, expanding the average interatomic separation as the alloy concentration of Am increases. Both Pu and Am spontaneously decay by {alpha}-emission creating self-damage in the lattice in the form of vacancy-interstitial pairs and their aggregates. At sufficiently low temperatures, the damage is frozen in place, but can be removed by thermal annealing at sufficiently high temperatures, effectively resetting the system to an undamaged condition. The magnetic susceptibility and magnetization are observed to increase systematically as a function of accumulated damage in the fcc {delta}-Pu{sub 1-x}Am{sub x} (x=0.224). Some results of these observations are reported here.
Date: December 14, 2006
Creator: McCall, S K; Fluss, M J; Chung, B W; McElfresh, M W & Haire, R G
Partner: UNT Libraries Government Documents Department

Influence of radiation damage and isochronal annealing on the magnetic susceptibility of Pu(1-x)Am(x) alloys

Description: Results of radiation damage in Pu and Pu{sub 1-x}Am{sub x} alloys studied with magnetic susceptibility, {chi}(T), and resistivity are presented. Damage accumulated at low temperatures increases {chi}(T) for all measured alloys, with the trend generally enhanced as the lattice expands. There is a trend towards saturation observable in the damage induced magnetic susceptibility data, that is not evident in similar damage induced resistivity data taken on the same specimen. A comparison of isochronal annealing curves measured by both resistivity and magnetic susceptibility on a 4.3at% Ga stabilized {delta}-Pu specimen show that Stage I annealing, where interstitials begin to move, is largely transparent to the magnetic measurement. This indicates that interstitials have little impact on the damage induced increase in the magnetic susceptibility. The isochronal annealing curves of the Pu{sub 1-x}Am{sub x} alloys do not show distinct annealing stages as expected for alloys. However, samples near 20% Am concentration show an unexpected increase in magnetization beginning when specimens are annealed to 35K. This behavior is also reflected in a time dependent increase in the magnetic susceptibility of damaged specimens indicative of first order kinetics. These results suggest there may be a metastable phase induced by radiation damage and annealing in Pu{sub 1-x}Am{sub x} alloys.
Date: May 2, 2008
Creator: McCall, S; Fluss, M; Chung, B & Haire, R
Partner: UNT Libraries Government Documents Department

Kondo-like 4f delocalization in Gd at high pressure

Description: We present resonant inelastic x-ray scattering (RIXS) and x-ray emission spectroscopy (XES) results which suggest Kondo-like aspects in the delocalization of 4f electrons in Gd metal to 113 GPa. Analysis of the RIXS data reveal a prolonged and continuous process throughout the entire pressure range, so that the volume collapse transition at 59 GPa is only part of the delocalization phenomenon. Moreover, the L{sub {gamma}1} XES spectra indicate no apparent change in the bare 4f moment across the collapse, suggesting that Kondo screening is responsible for the expected Pauli-like behavior in magnetic susceptibility.
Date: November 28, 2005
Creator: Maddox, B R; Lazicki, A; Yoo, C S; Iota, V; Chen, M; McMahan, A K et al.
Partner: UNT Libraries Government Documents Department

Quantum optics mini-program on fast light, slow light, and metamaterials.

Description: The topic of electromagnetic propagation in dielectric media has been enlivened in the past decade by a number of remarkable experimental results showing the technical ability to control the speed of light propagation in exotic ways. Light pulses have been observed travelling faster than c, or slowed by many orders of magnitude, or even stopped completely. All of thcse results require careful interpretation, and a variety of theoretical interpretations have been proposed and/or published, not all agreeing with each other. At the same time, in a lower frequency range than optical, rapid development of so-called meta-materials or double-negative materials has occurred. These materials are characterized by electric permittivity and magnetic permeability with very unconventional values, both quantities negative in some cases. Such unusual properties, especially when leading to a negative value for the group velocity, clearly indicate another possibility for control of light. Such materials are being improved rapidly, but independent of their implementation in the laboratory, their theoretical properties have led to dramatic predictions such as the existence of a perfect lens, Le., a finite lens (actually even planar-flat rather than parabolic) that can deliver an ideally sharp focus unaffected by diffractive effects. There are strong contentions currently being published that such predictions are erroneous
Date: January 1, 2002
Creator: Milonni, Peter W.
Partner: UNT Libraries Government Documents Department

Effect of rare-earth doping in RCrSb3 (R = La, Pr, Sm, and Gd)

Description: We report on the electrical resistivity and magnetic susceptibility of La or Gd doped RCrSb{sub 3} (R=La, Pr, Sm, and Gd). Single crystals were grown by increasing the nominal dopant by 25%. In general, two magnetic ordering transitions are found, T{sub C1} is attributed to ferromagnetic ordering of the itinerant Cr sub-lattice, and, at lower temperatures, T{sub C2} is attributed to ordering of the localized rare-earth sub-lattice. Alloying on the rare-earth site varies the de Gennes factor, DG = (g-1){sup 2}J(J+1), and dT{sub C1}/d(DG) = -2K, while dT{sub C2}/d(DG) = 5K. These ordering temperatures are found to converge at GdCrSb{sub 3}, where a single ferrimagnetic transition is found at T{sub C2} = 86 K due to an anti-alignment of the itinerant Cr moments and the localized rare-earth moments. Initially, for DG &lt; 3.5, the rare-earth moments are found to align ferromagnetically, and the paramagnetic Weiss temperature decreases at the same rate as T{sub C1}. But for DG &gt; 4.5, the rare-earth sub-lattice anti-alignes with respect to the Cr sub-lattice, and the Weiss temperature decreases five times as fast. In the region between (3.5 &lt; DG &lt; 4.5), a first order phase transition is found at T{sub C2}.
Date: November 8, 2005
Creator: Jackson, D D & Fisk, Z
Partner: UNT Libraries Government Documents Department

Structure and anisotropic properties of single crystals nickel doped barium iron arsenide

Description: The crystal structure, anisotropic electrical resistivity and magnetic susceptibility, as well as specific heat results of the pure single crystals of BaFe{sub 2}As{sub 2}, BaFeNiAs{sub 2}, and BaNi{sub 2}As{sub 2} are surveyed. BaFe{sub 2}As{sub 2} properties demonstrate the equivalence of C(T), Fisher's d({chi}T)/dT and d{rho}/dT results in determining the antiferromagnetic transition at T{sub N} = 132(1) K. BaNi{sub 2}As{sub 2} shows a structural phase transition from a high-temperature tetragonal phase to a low-temperature triclinic pol symmetry at T{sub 0} 131 K, with superconducting critical temperature well below at {Tc} 0.69 K. BaFeNiAs{sub 2} does not show any sign of superconductivity and gives behavioral similarity to BaCo{sub 2}As{sub 2}, a renomalized paramagnetic metal.
Date: January 1, 2009
Creator: Ronning, Filip; Bauer, Eric D; Sefat, A S; Jin, R; Mcguire, M A; Sales, B C et al.
Partner: UNT Libraries Government Documents Department